Button cover



FIG. 1 is a perspective view of a button cover showing the new design;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view;

FIG. 4 is a front view; and,

FIG. 5 is a rear view.

In the drawings, the broken lines depict environmental subject matter only and form no part of the claimed design. 

CLAIM The ornamental design for a button cover, as shown and described. 